/* =========================================================
   CIS 365 — Full Stack Web Development
   Design system: "the study notebook"
   ========================================================= */

:root {
  /* Palette */
  --paper: #F1F0EA;
  --paper-card: #FAFAF6;
  --paper-deep: #E7E4D9;
  --ink: #202C3C;
  --ink-soft: #56637A;
  --ink-faint: #8A93A3;
  --accent-gold: #B07C2C;
  --accent-gold-soft: #E7D2A6;
  --accent-berry: #7A2E3B;
  --accent-berry-soft: #E9D3D6;
  --accent-sage: #4C6B5B;
  --accent-sage-soft: #D4E0D8;
  --line: #D8D4C6;
  --shadow: 0 1px 2px rgba(32, 44, 60, 0.06), 0 6px 20px rgba(32, 44, 60, 0.06);

  /* Type */
  --font-display: "Fraunces", "Iowan Old Style", Georgia, serif;
  --font-body: "Source Sans 3", "Segoe UI", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Menlo, monospace;

  --radius: 10px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

/* Subtle paper texture via layered gradient — no external image */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    repeating-linear-gradient(180deg, rgba(32,44,60,0.015) 0px, rgba(32,44,60,0.015) 1px, transparent 1px, transparent 34px);
}

a { color: var(--accent-berry); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent-gold); }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink);
  font-weight: 600;
  letter-spacing: -0.01em;
}

code, pre {
  font-family: var(--font-mono);
  font-size: 0.88em;
}

pre {
  background: var(--ink);
  color: #EDE7D6;
  padding: 1.1rem 1.25rem;
  border-radius: var(--radius);
  overflow-x: auto;
  box-shadow: var(--shadow);
}

pre code { background: none; padding: 0; color: inherit; }

:not(pre) > code {
  background: var(--paper-deep);
  padding: 0.12em 0.4em;
  border-radius: 5px;
  color: var(--accent-berry);
}

/* Visible focus ring everywhere, respecting accessibility */
a:focus-visible, button:focus-visible, [tabindex]:focus-visible {
  outline: 3px solid var(--accent-gold);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}

/* =============== Top Bar =============== */
.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem 1.5rem;
  background: rgba(241, 240, 234, 0.92);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}

.topbar__brand {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.15rem;
  color: var(--ink);
  text-decoration: none;
}

.topbar__brand .code {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--accent-berry);
  background: var(--accent-berry-soft);
  padding: 0.2rem 0.5rem;
  border-radius: 5px;
}

.topbar__nav { display: flex; gap: 1.4rem; align-items: center; }
.topbar__nav a {
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.95rem;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
}
.topbar__nav a:hover, .topbar__nav a.is-active {
  color: var(--ink);
  border-bottom-color: var(--accent-gold);
}

/* =============== Layout shell =============== */
.shell {
  position: relative;
  z-index: 1;
  max-width: 1120px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 5rem;
}

.shell--wide { max-width: 1280px; }

/* =============== Hero =============== */
.hero {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 2.5rem;
  align-items: center;
  padding: 3rem 0 3.5rem;
  border-bottom: 1px solid var(--line);
  margin-bottom: 2.5rem;
}

.hero__eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-berry);
  margin: 0 0 0.9rem;
}

.hero h1 {
  font-size: clamp(2.1rem, 4vw, 3rem);
  line-height: 1.08;
  margin: 0 0 1rem;
}

.hero p.lede {
  color: var(--ink-soft);
  font-size: 1.12rem;
  max-width: 46ch;
  margin: 0 0 1.6rem;
}

.hero__actions { display: flex; gap: 0.9rem; flex-wrap: wrap; }

/* Signature element: the stitched bookmark ribbon */
.bookmark-figure {
  position: relative;
  justify-self: end;
  width: 220px;
  height: 300px;
}

.bookmark-figure svg { width: 100%; height: 100%; display: block; }

/* =============== Buttons =============== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.96rem;
  padding: 0.7rem 1.3rem;
  border-radius: 999px;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}
.btn:hover { transform: translateY(-1px); }

.btn--primary {
  background: var(--ink);
  color: var(--paper-card);
}
.btn--primary:hover { background: #14202E; color: var(--paper-card); }

.btn--ghost {
  background: transparent;
  border-color: var(--line);
  color: var(--ink);
}
.btn--ghost:hover { border-color: var(--accent-gold); color: var(--ink); }

.btn--sm { padding: 0.45rem 0.9rem; font-size: 0.85rem; }
.btn:disabled { opacity: 0.45; cursor: not-allowed; transform: none; }

/* =============== Progress =============== */
.progress-track {
  height: 8px;
  border-radius: 999px;
  background: var(--paper-deep);
  overflow: hidden;
}
.progress-track__fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-gold), var(--accent-berry));
  transition: width 0.4s ease;
}

.progress-label {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-soft);
  letter-spacing: 0.03em;
}

/* =============== Module / Lesson list (home) =============== */
.module-block { margin-bottom: 2.6rem; }

.module-block__head {
  display: flex;
  align-items: baseline;
  gap: 0.7rem;
  margin-bottom: 1rem;
}

.module-block__head h2 {
  font-size: 1.4rem;
  margin: 0;
}

.module-block__head .count {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-faint);
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

.lesson-card {
  position: relative;
  display: block;
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.3rem 1.4rem 1.1rem;
  text-decoration: none;
  color: var(--ink);
  box-shadow: var(--shadow);
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.lesson-card:hover { transform: translateY(-2px); border-color: var(--accent-gold); color: var(--ink); }

.lesson-card__num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent-berry);
  display: block;
  margin-bottom: 0.4rem;
}

.lesson-card h3 {
  font-size: 1.08rem;
  margin: 0 0 0.4rem;
  line-height: 1.3;
}

.lesson-card p {
  font-size: 0.92rem;
  color: var(--ink-soft);
  margin: 0 0 0.7rem;
}

.lesson-card__meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--ink-faint);
}

.badge-done {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  color: var(--accent-sage);
  font-weight: 600;
  font-size: 0.78rem;
}
.badge-done::before { content: "✓"; }

/* =============== Lesson page layout =============== */
.lesson-layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 2.5rem;
  align-items: start;
}

/* Stitched tab rail — the recurring signature element */
.tab-rail {
  position: sticky;
  top: 90px;
  border-left: 3px dashed var(--line);
  padding-left: 1.1rem;
}

.tab-rail__module {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 1.2rem 0 0.5rem;
}
.tab-rail__module:first-child { margin-top: 0; }

.tab-rail a {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--ink-soft);
  font-size: 0.9rem;
  padding: 0.32rem 0;
  position: relative;
}

.tab-rail a .dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--paper-deep);
  border: 1px solid var(--line);
  flex-shrink: 0;
}

.tab-rail a.is-active { color: var(--ink); font-weight: 600; }
.tab-rail a.is-active .dot { background: var(--accent-gold); border-color: var(--accent-gold); }
.tab-rail a.is-done .dot { background: var(--accent-sage); border-color: var(--accent-sage); }
.tab-rail a:hover { color: var(--ink); }

.lesson-page {
  background: var(--paper-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 2.6rem 3rem;
  box-shadow: var(--shadow);
}

@media (max-width: 860px) {
  .lesson-layout { grid-template-columns: 1fr; }
  .tab-rail { position: static; border-left: none; padding-left: 0; }
  .lesson-page { padding: 1.8rem 1.4rem; }
  .hero { grid-template-columns: 1fr; }
  .bookmark-figure { justify-self: start; width: 160px; height: 210px; }
}

.lesson-content h1 { font-size: 2rem; margin-top: 0; }
.lesson-content h1 + p em { color: var(--ink-faint); font-style: normal; font-family: var(--font-mono); font-size: 0.85rem; }
.lesson-content h2 {
  font-size: 1.35rem;
  margin-top: 2.2rem;
  padding-top: 0.4rem;
  border-top: 1px solid var(--line);
}
.lesson-content h2:first-of-type { border-top: none; margin-top: 1.6rem; }
.lesson-content ul, .lesson-content ol { padding-left: 1.4rem; }
.lesson-content li { margin-bottom: 0.35rem; }
.lesson-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.92rem;
}
.lesson-content th, .lesson-content td {
  text-align: left;
  border-bottom: 1px solid var(--line);
  padding: 0.5rem 0.7rem;
}
.lesson-content th { font-family: var(--font-mono); font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.04em; color: var(--ink-soft); }

.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

/* =============== Quiz =============== */
.quiz {
  margin-top: 2.8rem;
  padding: 1.8rem 2rem;
  background: var(--paper-deep);
  border-radius: var(--radius);
  border: 1px solid var(--line);
}

.quiz__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.quiz__head h3 { margin: 0; font-size: 1.1rem; }

.quiz-q { margin-bottom: 1.4rem; }
.quiz-q p.stem { font-weight: 600; margin: 0 0 0.6rem; }

.quiz-choice {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  padding: 0.55rem 0.7rem;
  border-radius: 8px;
  cursor: pointer;
  border: 1px solid transparent;
  font-size: 0.94rem;
}
.quiz-choice:hover { background: rgba(32,44,60,0.04); }
.quiz-choice input { margin-top: 0.25rem; }

.quiz-choice.is-correct { background: var(--accent-sage-soft); border-color: var(--accent-sage); }
.quiz-choice.is-wrong { background: var(--accent-berry-soft); border-color: var(--accent-berry); }

.quiz__result {
  margin-top: 1rem;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--ink-soft);
}

/* =============== Interactive widgets =============== */
.interactive { margin-top: 2.8rem; }

.widget {
  background: var(--ink);
  color: #EDE7D6;
  border-radius: var(--radius);
  padding: 1.4rem 1.5rem 1.6rem;
  box-shadow: var(--shadow);
}

.widget__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.widget__label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.03em;
  color: var(--accent-gold-soft);
}

.widget .progress-label { color: #B7C0CE; }

.widget__actions { display: flex; gap: 0.5rem; }
.widget .btn--ghost { border-color: rgba(237,231,214,0.3); color: #EDE7D6; }
.widget .btn--ghost:hover { border-color: var(--accent-gold); }

/* Playground */
.playground {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  min-height: 260px;
}

.playground__editor { display: flex; flex-direction: column; }

.playground__tabs { display: flex; gap: 0.3rem; margin-bottom: 0.5rem; }
.playground__tabs button {
  background: transparent;
  border: 1px solid rgba(237,231,214,0.25);
  color: #B7C0CE;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.3rem 0.7rem;
  border-radius: 6px 6px 0 0;
  cursor: pointer;
}
.playground__tabs button.is-active { background: #14202E; color: var(--accent-gold-soft); border-color: var(--accent-gold-soft); }

.playground__editor textarea {
  flex: 1;
  min-height: 220px;
  background: #14202E;
  color: #EDE7D6;
  border: 1px solid rgba(237,231,214,0.15);
  border-radius: 0 8px 8px 8px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.8rem;
  resize: vertical;
}

.playground__preview {
  width: 100%;
  min-height: 260px;
  background: #fff;
  border: none;
  border-radius: 8px;
}

@media (max-width: 720px) {
  .playground { grid-template-columns: 1fr; }
}

/* API tester */
.api-tester__presets { display: flex; gap: 0.5rem; flex-wrap: wrap; margin-bottom: 0.9rem; }
.api-tester__bar { display: flex; gap: 0.6rem; margin-bottom: 0.8rem; }
.api-tester__bar select, .api-tester__bar input {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.5rem 0.7rem;
  border-radius: 6px;
  border: 1px solid rgba(237,231,214,0.25);
  background: #14202E;
  color: #EDE7D6;
}
.api-tester__bar input { flex: 1; }
.api-tester__error { color: #E7B4B4; font-size: 0.88rem; }
.api-tester__status { font-family: var(--font-mono); font-size: 0.85rem; margin: 0 0 0.5rem; }
.api-tester__response pre {
  max-height: 320px;
  overflow: auto;
  margin: 0;
}

/* Markdown live preview */
.md-preview {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
.md-preview textarea {
  min-height: 260px;
  background: #14202E;
  color: #EDE7D6;
  border: 1px solid rgba(237,231,214,0.15);
  border-radius: 8px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.9rem;
  resize: vertical;
}
.md-preview__output {
  background: var(--paper-card);
  color: var(--ink);
  border-radius: 8px;
  padding: 1rem 1.2rem;
  overflow: auto;
}
.md-preview__output.lesson-content h1 { font-size: 1.4rem; }
.md-preview__output.lesson-content h2 { font-size: 1.1rem; border-top: none; margin-top: 1rem; }

@media (max-width: 720px) {
  .md-preview { grid-template-columns: 1fr; }
}

/* Regex tester */
.regex-tester__bar { display: flex; align-items: center; gap: 0.4rem; margin-bottom: 0.8rem; }
.regex-tester__slash { font-family: var(--font-mono); color: var(--accent-gold-soft); }
.regex-tester__pattern, .regex-tester__flags {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  padding: 0.4rem 0.6rem;
  border-radius: 6px;
  border: 1px solid rgba(237,231,214,0.25);
  background: #14202E;
  color: #EDE7D6;
}
.regex-tester__pattern { flex: 1; }
.regex-tester__flags { width: 70px; }
.regex-tester textarea {
  width: 100%;
  min-height: 90px;
  background: #14202E;
  color: #EDE7D6;
  border: 1px solid rgba(237,231,214,0.15);
  border-radius: 8px;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  padding: 0.7rem;
  resize: vertical;
}
.regex-tester__output {
  background: var(--paper-card);
  color: var(--ink);
  border-radius: 8px;
  padding: 0.9rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  line-height: 1.7;
  white-space: pre-wrap;
}
.regex-tester__output mark {
  background: var(--accent-gold-soft);
  color: var(--ink);
  border-radius: 3px;
  padding: 0 2px;
}

/* Node sandbox (StackBlitz launch-in-new-tab) */
.widget pre {
  background: #14202E;
  margin: 0 0 1rem;
  max-height: 320px;
  overflow: auto;
}

/* =============== Footer =============== */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 2.2rem 1.5rem;
  text-align: center;
  color: var(--ink-faint);
  font-size: 0.85rem;
  position: relative;
  z-index: 1;
}
.site-footer a { color: var(--ink-soft); }

/* Utility */
.text-muted { color: var(--ink-soft); }
.mt-0 { margin-top: 0; }
.center { text-align: center; }
.skeleton { color: var(--ink-faint); font-family: var(--font-mono); font-size: 0.85rem; }